---
title: "A circuit consists of a real battery with electromotive force \\(\\varepsilon\\) and internal resistance \\(r\\) connected across a variable resistor of resistance \\(R\\). The graph shows the electric power \\(P\\) dissipated by the variable resistor as a function of \\(R\\). Based on the graph, what is the electromotive force \\(\\varepsilon\\) of the battery?"
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url: "https://nerd-notes.com/ubq/117417/"
date_modified: "2026-08-04T06:52:05+00:00"
---

# A circuit consists of a real battery with electromotive force \(\varepsilon\) and internal resistance \(r\) connected across a variable resistor of resistance \(R\). The graph shows the electric power \(P\) dissipated by the variable resistor as a function of \(R\). Based on the graph, what is the electromotive force \(\varepsilon\) of the battery?

A circuit consists of a real battery with electromotive force \(\varepsilon\) and internal resistance \(r\) connected across a variable resistor of resistance \(R\). The graph shows the electric power \(P\) dissipated by the variable resistor as a function of \(R\). Based on the graph, what is the electromotive force \(\varepsilon\) of the battery?

![A quantitative graph showing power P in watts on the vertical axis versus resistance R in ohms on the horizontal axis. The vertical axis ranges from 0 to 10 W with grid lines and tick marks every 1 W. The horizontal axis ranges from 0 to 16 ohms with grid lines and tick marks every 2 ohms. A smooth curve starts at the origin (0,0), rises continuously to a single maximum peak at (4, 9), and then smoothly decreases as R increases, passing through grid intersections at (2, 8), (8, 8), (12, 6.75), and (16, 5.76). No other text, labels, or construction lines appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1785826325-jB63Of.jpg)

- **A.** \(3.0 \text{ V}\)
- **B.** \(6.0 \text{ V}\)
- **C.** \(12 \text{ V}\)
- **D.** \(24 \text{ V}\)

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/117417/*